From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Haiwei Li <lihaiwei@tencent.com>
Subject: Re: [PATCH v4 2/7] KVM: X86: Enable fastpath when APICv is enabled
Date: Mon, 4 May 2020 19:06:53 +0200 [thread overview]
Message-ID: <906b09e3-edcf-9d0e-e43b-ae77741c55e9@redhat.com> (raw)
In-Reply-To: <87a72tf67l.fsf@vitty.brq.redhat.com>
On 30/04/20 15:34, Vitaly Kuznetsov wrote:
>> static enum exit_fastpath_completion vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
>> {
>> - if (!is_guest_mode(vcpu)) {
>> + if (!is_guest_mode(vcpu) && vcpu->arch.apicv_active) {
>> switch (to_vmx(vcpu)->exit_reason) {
>> case EXIT_REASON_MSR_WRITE:
>> return handle_fastpath_set_msr_irqoff(vcpu);
> I think that apicv_active checks are specific to APIC MSRs but
> handle_fastpath_set_msr_irqoff() can handle any other MSR as well. I'd
> suggest to move the check inside handle_fastpath_set_msr_irqoff().
>
> Also, enabling Hyper-V SynIC leads to disabling apicv. It it still
> pointless to keep fastpath enabled?
Indeed, only fast paths that only apply to apicv should be disabled (and
ideally there should be a WARN_ON in the code that doesn't support !apicv).
Paolo
next prev parent reply other threads:[~2020-05-04 17:07 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 6:23 [PATCH v4 0/7] KVM: VMX: Tscdeadline timer emulation fastpath Wanpeng Li
2020-04-28 6:23 ` [PATCH v4 1/7] KVM: VMX: Introduce generic fastpath handler Wanpeng Li
2020-04-30 13:28 ` Vitaly Kuznetsov
2020-05-01 14:11 ` Sean Christopherson
2020-05-01 22:52 ` Wanpeng Li
2020-04-28 6:23 ` [PATCH v4 2/7] KVM: X86: Enable fastpath when APICv is enabled Wanpeng Li
2020-04-30 13:34 ` Vitaly Kuznetsov
2020-05-04 17:06 ` Paolo Bonzini [this message]
2020-04-28 6:23 ` [PATCH v4 3/7] KVM: X86: Introduce more exit_fastpath_completion enum values Wanpeng Li
2020-04-28 6:23 ` [PATCH v4 4/7] KVM: X86: Introduce kvm_vcpu_exit_request() helper Wanpeng Li
2020-04-28 6:23 ` [PATCH v4 5/7] KVM: VMX: Optimize posted-interrupt delivery for timer fastpath Wanpeng Li
2020-04-30 13:32 ` Paolo Bonzini
2020-04-30 23:43 ` Wanpeng Li
2020-04-28 6:23 ` [PATCH v4 6/7] KVM: X86: TSCDEADLINE MSR emulation fastpath Wanpeng Li
2020-04-28 9:58 ` 林鑫龙
2020-04-28 10:05 ` Wanpeng Li
2020-04-28 6:23 ` [PATCH v4 7/7] KVM: VMX: Handle preemption timer fastpath Wanpeng Li
2020-05-04 17:22 ` [PATCH v4 0/7] KVM: VMX: Tscdeadline timer emulation fastpath Paolo Bonzini
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